With the advent of third and fourth generation CT scanners, invasive and interventive procedures that are performed under CT guidance are now used extensively. CT guided needle aspiration biopsies have been highly successful and have alleviated the need for diagnostic surgery in the vast majority of cases: (Haaga J., Lipuma J., Bryon P., Balsara V., Cohn A., Clinical comparison of small and large caliber cutting needles for biopsy. Radiology 164:665-667, March 1983; Mulari Sunduram, et al., Utility of CT guided abdominal aspiration procedures. AJR 139:1111-1115, December 1982; Harvey M. Goldstein, et al., Percutaneous fine needle aspiration biopsy of pancreatic and other abdominal masses. Radiology 123:319-322, May 1977; and Robert Isler, et al., Tissue core biopsy of abdominal tumors with a 22 gauge cutting needle. AJR 136:725-728, April 1981). In addition, CT now guides the drainage of abdominal abcesses by way of a percutaneous route eliminating the need for repeat surgery. At the present time, however, all of these procedures are guided by hand, consequently it is usually a time-consuming process that requires multiple needle manipulations with repeat scanning to verify the position of the needle. Because of this lack of proper instrumentation, it can take as long as an hour to biopsy a 2-3 cm lesion in the liver of a patient.
CT stereotaxis is a well established procedure for the head (Brown, R. A., A computerized tomography-computer graphics approach to stereotaxic localization. J. Neurosurg., 50:715-720, 1979; Brown, R. A., A stereotactic head frame for use with CT body scanners. Invest. Radiol., 14:300, 1979; Brown, R. A., Roberts, T. S., Osborn, A. G., Stereotaxic frame and computer software for CT-directed neurosurgical localization. Invest. Radiol., 15:308-312, 1980; and Roberts, T. S., Brown, R. A., Technical and clinical aspects of CT-directed stereotaxis. Applied Neurophysiology, 43:170-171, 1980). The brain, because of its consistent relationship to the boney skull, can have a rigid frame attached to it which can then provide the needed reference coordinates from which various paths can be calculated. It should be noted that in all of the present stereotaxic devices for the brain, the reference coordinates are taken from the attached frame not the patient's skin and referenced to the target. The body, however, does not have the constant relationships of its surface anatomy to the underlying organs. In addition, there is no structure to which a rigid frame can be attached. To add to the difficulties, many of the organs within the abdominal cavity move with respiration so that with the changes in the phase of respiration, the relationship of the organs to the surface are different. It is for these reasons that at present there has been no published attempt to use CT stereotaxis in the guiding of probes or needle into the neck, chest, abdomen, pelvis, and extremities.